83 lines
1.6 KiB
C
83 lines
1.6 KiB
C
#include <kernel/util.h>
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typedef uint64_t word_t;
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#define STATE_SIZE 312
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#define MIDDLE 156
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#define INIT_SHIFT 62
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#define TWIST_MASK 0xb5026f5aa96619e9
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#define INIT_FACT 6364136223846793005
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#define SHIFT1 29
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#define MASK1 0x5555555555555555
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#define SHIFT2 17
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#define MASK2 0x71d67fffeda60000
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#define SHIFT3 37
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#define MASK3 0xfff7eee000000000
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#define SHIFT4 43
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#define LOWER_MASK 0x7fffffff
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#define UPPER_MASK (~(word_t)LOWER_MASK)
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static word_t state[STATE_SIZE];
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static size_t index = STATE_SIZE + 1;
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static void seed(word_t s)
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{
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index = STATE_SIZE;
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state[0] = s;
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for (size_t i = 1; i < STATE_SIZE; i++) {
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state[i] = (INIT_FACT
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* (state[i - 1] ^ (state[i - 1] >> INIT_SHIFT)))
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+ i;
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}
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}
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static void twist(void)
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{
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for (size_t i = 0; i < STATE_SIZE; i++) {
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word_t x = (state[i] & UPPER_MASK)
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| (state[(i + 1) % STATE_SIZE] & LOWER_MASK);
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x = (x >> 1) ^ (x & 1 ? TWIST_MASK : 0);
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state[i] = state[(i + MIDDLE) % STATE_SIZE] ^ x;
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}
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index = 0;
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}
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static word_t mt_random(void)
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{
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if (index >= STATE_SIZE) {
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twist();
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}
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word_t y = state[index];
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y ^= (y >> SHIFT1) & MASK1;
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y ^= (y << SHIFT2) & MASK2;
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y ^= (y << SHIFT3) & MASK3;
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y ^= y >> SHIFT4;
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index++;
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return y;
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}
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void init_random(uint64_t seedvalue)
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{
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seed(seedvalue);
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}
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bool fill_random(void *p, unsigned int size)
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{
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unsigned char *dst = p;
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uint64_t w = mt_random();
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unsigned char *src = (unsigned char *)&w;
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for (size_t i = 0, j = 0; i < size; i++, j++) {
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dst[i] = src[j];
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if (j == (sizeof w) - 1) {
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w = mt_random();
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j = 0;
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}
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}
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return true;
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}
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